Mogadishu, Somalia - A land mine killed one person and wounded eight in a rare attack on a mosque in the Somali capital on Tuesday, a day of chaotic violence that left at least another 15 people dead and scores wounded.

Witnesses said the mine exploded as worshippers were going to the Abu Hureyra mosque in Bakara Market, an area used as a base by rebels fighting the government and African Union (AU) peackeeping troops in Somalia.

Residents said nine people died when mortar shells hit a house in the south of the city, two rebels and a government soldier were killed in fighting near Bakara Market and two AU soldiers were wounded when they stopped a suicide bomber from ramming a truck laden with explosives into their base.

"We have received 57 injured people today. Three of them died in the hospital," Mohamed Yusuf, director of the Madina Hospital, told Reuters.

Insurgents have been fighting the Western-backed government in the Horn of Africa nation since the start of 2007. The rebel groups now control much of southern and central Somalia while the government is hemmed into a few blocks of the capital.

At least 21,000 civilians have been killed since the start of the insurgency. Aid agencies and rights groups have become increasingly concerned about indiscriminate shelling and some have accused combatants on all sides of war crimes.

An African Union peacekeeping force made up of soldiers from Uganda and Burundi is propping up the government in Mogadishu, and guarding key sites such as the airport and seaport.

SUICIDE BOMBING

The International Committee of the Red Cross said last week that the two hospitals it supports in Mogadishu had received 1,900 patients with weapon wounds between January and mid-April, and hundreds had been killed as result of the fighting.

It was not clear who was behind the mosque explosion, though residents suspected it might have been infighting between the two insurgent groups that dominate the Bakara Market.

"We hear about explosions at mosques in Iraq, so this is an amazing thing to happen in Somalia," witness Abdallahi said.

Hizbul Islam and al Qaeda-linked al Shabaab are the two main rebel groups in Somalia. While the two frequently clash in the south of the country for control of strategic towns, they are usually on the same side against the government in the capital.

"They claim to be religious. But clerics don't behead, kill and detonate people," said Mogadishu resident Mohamed. "It really is terrible, this could stop people going to mosques."

Al Shabaab claimed responsibility for a suicide car bombing on Tuesday that targeted a new AU base set up last week in the Shangani area of the capital, north of the presidential palace.

Major Barigye Ba-hoku, spokesman for the AU force, said the vehicle was blown up before it could ram into the new base, which is manned by Ugandan soldiers.

"We have foiled the attempt, we have destroyed the would-be suicide car bomb. Two of our soldiers who destroyed the car sustained minor injuries," he told Reuters.